ULURU (AYERS ROCK)
Uluru is predominantly composed of coarse-grained arkose (a type of sandstone with an abundance of feldspar) and some conglomerate. Iron-bearing minerals weathered by oxidation give the rock its red-brown rusty colour, though fresh rock surfaces are grey. It covers 3.3 square kilometres and is 9.4 kilometres around its base. It reaches 345 metres above the plains.
Over 600 million years ago large amounts of Central Australia were below sea level within the Amadeus Basin. Rivers brought large quantities of sedimentary material into the Amadeus Basin. 500 million years ago the Basin started to rise out of the sea, and the sediment from the rivers began to form alluvial fans. The sediment from which Uluru formed came from a section one of these alluvial fans. Over time the sea re-entered the Basin and more sedimentary material was deposited then lithified.
Between 300 and 400 million years ago there was a prolonged period of mountain building; the future Uluru was tilted at almost 90° to create the present vertical orientation of the strata. There were millions more years of weathering but Uluru, Kata Tjuta (the Olgas, 35 km to the west) and Atila (Mount Connor, about 100km east of Uluru) were made of harder rock than that which surrounded them, so were less susceptible to erosion. The landscape was smoothed out by the wetter climate of 60-70 million years ago.
This diagram shows the underlying tectonics:http://upload.wikimedia.org/wikipedia/commons/9/95/Schema_Kata_Tjuta_Uluru.png
Read more: http://www.ga.gov.au/education/geoscience-basics/landforms/significant-rock-features.html; http://www.environment.gov.au/parks/uluru/nature-science/geology.html; http://www.wayoutback.com.au/Uluru-(Ayers-Rock)/Uluru-Geology.aspx